In recent years, deep brain stimulation (DBS) has shown a great potential as an effective treatment for many neurological and neurodegenerative diseases. DBS is already FDA-approved as a treatment for diseases like essential tremor, Parkinson's disease, and dystonia. DBS has also been tested or proposed as a remedy for disorders like chronic pain, major depression, obsessive-compulsive disorder, dementia and schizophrenia (Schlaepfer, T. E., B. Bewernick, S. Kayser and D. Lenz (2011), “Modulating affect, cognition, and behavior—prospects of deep brain stimulation for treatment-resistant psychiatric disorders,” Front Integr Neurosci 5: 29; Hoffman, R. E., R. Gueorguieva, K. A. Hawkins, M. Varanko, N. N. Boutros, Y. T. Wu, K. Carroll and J. H. Krystal (2005), “Temporoparietal transcranial magnetic stimulation for auditory hallucinations: safety, efficacy and moderators in a fifty patient sample,” Biol Psychiatry 58(2): 97-104; Jin, Y., S. G. Potkin, A. S. Kemp, S. T. Huerta, G. Alva, T. M. Thai, D. Carreon and W. E. Bunney, Jr. (2006), “Therapeutic effects of individualized alpha frequency transcranial magnetic stimulation (alphaTMS) on the negative symptoms of schizophrenia,” Schizophr Bull 32(3): 556-561; and Kuhn, J., M. Bodatsch, V. Sturm, D. Lenartz, J. Klosterkotter, P. J. Uhlhaas, C. Winter and T. O. Grundler (2011), “[Deep brain stimulation in schizophrenia],” Fortschr Neurol Psychiatr 79(11): 632-641). In many cases, DBS treatment seems to be able to stop or slow the disease process and improve symptoms and functioning for patients. Although DBS is so promising, it is still an invasive method and requires brain surgery through the skull and insertion of electrodes into deep brain regions. The surgery can potentially damage existing functional brain cells and is usually performed as a last resort. The situation has not only restricted the number of patients treated, but has also limited the opportunity to explore the full potential of the technique.
Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation method. TMS uses transient pulse field induced currents to cause neuronal depolarization and hyperpolarization in brain cortices. It induces a small electrical current, which stimulates nerve cells including their branches and allows for the study of brain functions and the development of new treatments for brain disorders. Currently there are many coil designs with a few of them on the market and many on the drawing board, all of which struggle with the inability to stimulate the brain with focus and depth at the same time. Commonly used coils, including the circular coil shown in FIG. 1(a), and the so-called figure 8 coils shown in FIG. 1(b), can only stimulate superficial areas of the brain (Roth, Y., A. Amir, Y. Levkovitz and A. Zangen (2007), “Three-dimensional distribution of the electric field induced in the brain by transcranial magnetic stimulation using figure-8 and deep H-coils,” J Clin Neurophysiol 24(1): 31-38; Deng, Z. D., S. H. Lisanby and A. V. Peterchev (2013), “Coil design considerations for deep transcranial magnetic stimulation,” Clin Neurophysiol; and Roth, Y., G. S. Pell and A. Zangen (2013), “Commentary on: Deng et al., Electric field depth-focality tradeoff in transcranial magnetic stimulation: simulation comparison of 50 coil designs,” Brain Stimul 6(1): 14-15).
The only approved and commercially available coil that is promoted as a deep brain TMS, is the H-coil TMS, as shown by FIG. 1(c), by Brainsway of Jerusalem, Israel. However, the H-coil still generates currents that are mostly circulating around the outer region of the brain, causing some increased depth of stimulation through summation but also affecting much wider cortical regions of the brain (Roth et al. 2007). Loss of focality is a trade-off for depth in H-coils as in all other coils currently available or conceived (Deng et al. 2013; Roth et al. 2013; Roth et al. 2007). Another limitation of some of these coils is that they require factory-wired configurations and can only target one predetermined area per coil. The hardware-to-brain inflexibility limits research and clinical applications, which often require testing of different anatomic locations, or personalized localization in different patients to achieve maximum benefit. Thus far, the figure-8 coil has the best combination of focality and depth. Its focality is achieved by summing one clockwise and one counter-clockwise circular field at the middle, making the focality of the induced currents more predictable. However, the resolution is modest and the stimulation does not go very deep.
In light of the foregoing limitations, there is a need for methods and systems that provide noninvasive controllable DBS, and also stimulations that are capable of operating effectively deep within the body. However, achieving the above purposes and/or benefits is not a necessary feature to each of the exemplary embodiments and claims may recite subject matter that does not achieve the above stated purpose.